ecm motors?

[ishium 80439]

What do you know about ECM motors? I hadn't heard of them until yesterday when a client of mine inquired about them. He owns a 3 story building w/ ~22,000 total sf and ~15,000 of tenant space (short term residential units) that he cools w/ 3 roof top swamp coolers. He asked me my opinion about swapping out the existing motors (208V 6.6A 1740RPM 1.5HP according to the name plate) w/ ECM units. As I had never heard of them I basically told him that I had no opinion but I would look into them. A quick google search yielded what basically seemed to be promotional material. So my question is does anyone have any experience w/ these, especially a cost/ benefit analysis? Any ideas how much more these cost as compared to a standard wound motor? Longevity? Payback time? Availibility? Any feedback would be greatly appreciated.

 

[winnie]

Once marketing gets its hand on a name, it can change to have all sorts of different meanings, some dubious at best.

ECM simply means 'electronically commutated motor'. In other words, a transistor or other semiconductor switch is used to the job of the commutator and brushes in brush motor (DC or universal). You may also see the term 'Brushless DC' motor used.

While there are distinctions in terms of raw motor efficiency, motor size, specifics of how the switches get controlled, etc., for the very brief overview, simply remember that ECM motors are essentially motors operated on a variable speed drive.

If you have an application where a variable speed motor will make the _load_ more efficient (air movers are a perfect example), then using a VSD can provide substantial savings.

Where you will see differences between a conventional induction motor and a fancier ECM is in the size of the motor itself, and perhaps a point or two of efficiency at the motor itself. But your big energy savings will come from better control of the process itself, not the motor.

-Jon